Physics for…

The minor adventures of physics major Jay Waller, showing that physics is everywhere.

. . . a first date

Jay Waller decided on a quiet, dimly lit Italian restaurant, complete with old wine bottles and romantic candles. After a bottle of white wine arrived, he poured his date a glass and then called her attention to the play of bright lines and spots that danced on the tablecloth as chance disturbance (actually his knee) gently shook the table. He casually explained how people have spent a long time trying to understand such plays of light, called caustics, which are due to how the surfaces of the wine and the wine glass fold the rays of candle light onto themselves, focusing the rays to form especially bright places. The pattern on the tablecloth is actually a two-dimensional slice through a three-dimensional pattern. To show this, Jay moved his hand through the pattern from the tablecloth to the wineglass, to show her how the lines changed in midair. Surely, he thought, this would produce a second date with her.

But then disaster hit. As they waited for the appetizers, he told her just how wonderful her eyes were, being so blue. He quickly explained the blue was due to the scatter of blue light out of the white light illuminating the iris. Tiny particles (including proteins and fats) in the iris scatter more blue light back outward than the other colors. If the back of the iris is generally black, then the blue light can be striking, as in her gorgeous eyes. Only then did she inform him that her eyes were, in fact, green. And as he glanced at them, he knew from her piercing look (a green that almost glowed in the dark) that there would be no second date with her.

. . . a dark room

As finals week loomed closer, Jay Waller was spending so much time in dark closets, seemingly a perfect excuse for not studying for the physics final exam, that his classmates began to worry about him. (“Do you think Jay is actually a vampire?” “What is he doing in the closet?”) Some of them had even begun a Google search for 12-step programs for closet fanatics.

However, what they did not realize was that Jay wasn’t just sitting there in some depraved and depressed state. In fact, he was doing Flying Circus of Physics stuff, using wintergreen mints, a mirror, and the flash unit of a camera. After dark adapting his eyes (which took about 15 minutes), Jay held the mirror at a comfortable distance in front of his face and chomped down on the wintergreen mints while keeping his lips open. Each bite produced a flash of blue light, the so-called sparking that had been discovered decades ago when wintergreen mints first became available. He chomped and chomped, fascinated by the bursts of blue light. He realized that if he ever got a chance at a second date with someone, this was the ideal physics (and the ideal location) to dazzle her. Well, maybe.

After some 30 minutes of sparking, he got to work on his physics class: He held his textbook in front of him at its normal distance for reading, flashed the camera strobe to briefly illuminate the open page, and then very carefully fixed his gaze in one direction, with no motion of his eyes. Although he could perceive nothing of the printed page during the brief (and blinding) flash of light, a positive afterimage soon appeared in which the page looked almost normal, as if he were seeing a photograph. If he moved his eyes, the image would immediately disappear, but if he held them steady, he could mentally run his attention along each line of text and then down the page, so that he can read the page. Figures and photographs were easily recognized.

Jay’s friends were so worried about him that they stopped studying for the physics final. Jay, however, went into the exam with almost a photographic memory of the textbook pages and “aced” the exam.

(items 5.19 and 7.15 in the book)

. . . a tedious lecture

Jay slumped in the chair, with sleep pressing down on his eyelids, as the instructor added yet another superscript to the symbol T on the chalkboard. The instructor had already placed two superscripts and three subscripts on the symbol, each depicting some special feature of a type of temperature. At this point, only the instructor knew what was going on.

Jay needed something to stay awake, to wrestle his mind back from the black hole of a PChem class. “Ah, think back to the Flying Circus of Physics,” he muttered to himself, but there was actually no need to be quiet because the nearby students were comatose long ago. In fact, Jay was not sure that they were still breathing.

Blind spot First, Jay closed one eye and carefully moved his view from the other eye near the instructor, until the instructor’s head suddenly disappeared. The blind spot of that eye (where the nerve connections breached the retina) was positioned just where the image of the instructor’s head fell. The voice, however, droned on. (item 7.3 here at this web site and also in the book)

Rhino-optical effect Next, with one eye still closed, Jay turned his head away from the instructor until the instructor was just barely visible near the nose side of Jay’s view with the open eye. Then, keeping his head steady, Jay rotated the gaze of that open eye toward the instructor, and the instructor fully disappeared, hidden by the nose. The instructor was just barely visible when Jay looked straight ahead but not when Jay actually turned his eye toward the instructor. (item 7.21 in the book)

Phosphenes With both eyes closed, Jay gently rubbed a finger against one of the eyelids, applying a slight pressure to the eye ball. As he moved the finger, subtle, dull lights appeared in his view, the so-called prisoner’s cinema that a prisoner in dark confinement might see due to lack of optical stimulation. Truck drivers also see it when driving through an environment with little change, such as might occur during a night-time drive through falling snow. When Jay pressed against both eyes simultaneously, geometric figures would sometimes appear. (item 7.7 in the book)

Illusionary dots Jay pulled out his permanent-ink pen and began to draw solid black squares on a sheet of white paper, with narrow white channels left between adjacent squares. At the “intersections” of the white channels (as if each were a traffic intersection between two perpendicular streets), fuzzy, ill-defined dark spots briefly appeared, although he could not fix his gaze on one, to make it last long enough to be seen clearly. Apparently his visual system, lit up by the nearby sharp edges of the squares, produced the illusion that the center of each intersection was darker than the rest of the intersection. (item 7.13 in the book)

Suddenly, Jay looked up to find that he was the only one left in the room. He had survived another PChem lecture! However, he still had half the semester to go. He would need a lot more Flying Circus physics get through the rest of the lectures.

. . . a night too noisy for sleep

Jay woke up just before the train hit him. At least, that is what it sounded like. But then, in the dark of his bedroom, he finally understood where the noise was coming from. Not from a train, but from his roommate, snoring as if he were imitating a jackhammer breaking apart concrete.

Jay, being a physics major, knew how that snoring sound was produced. Because his roommate had his mouth closed, whenever he inhaled, he pulled air up through the nose and down into the throat, past the soft pallet at the back of the mouth. The flow down into the throat was constricted, which means that the speed of the air flow must increase there, which means that the air pressure must decrease.

The problem with Jay’s roommate was that the pressure decreased enough to pull the soft pallet onto the back of the throat. Almost immediately the soft pallet flopped back onto the tongue and then back to its proper position, only to repeat the motion continuously in a complicated oscillation.

That motion of the soft pallet disrupted the airflow, creating turbulence, that is, sound waves in a range of wavelengths. Some of the wavelengths were just right to set up resonance in the nasal cavity, throat, and mouth. So, what Jay was hearing was physics in action --- speed increase of a constricted flow, a resulting pressure decrease in the air, oscillations of the soft pallet, turbulence in the air, sound production, and acoustic resonance. Lovely physics, but probably not so lovely at 3:00 AM.

So, physics or not, Jay rolled his roommate onto his side, put a pillow over his head (resisting the urge to compress the pillow until the breathing stopped entirely), and then pulled the covers over the head. The noise died out (but not the roommate).

However, there was still noise, now from overhead. The woman living above him was apparently walking around in high heels on the wood floor.

But wait, he thought, that does not make sense. Clicking heels onto a wood floor produces high frequency sounds --- click, click, click. We all hear it when high heels click along any hard floor. Tonight, Jay was hearing low frequency sounds, as if elephants were dancing in the upstairs apartment.

Then he realized what was happening. As the woman walked across the suspended floor, she caused it to oscillate like a large drumhead, sending out largely low frequency sound waves. Jay dialed the upstairs neighbor on his phone and, as soon as the neighbor picked up her phone, he shouted, “Would you PLEASE not dance around on my ceiling in high heels?”

On the other end, a man with a husky voice answered in slow words, “I don’t dance in heels, but if I ever see you, I’ll dance on your face!” Then Jay remembered that last week the woman had moved out, to be replaced by a member of the Hell’s Angels.

Although Jay’s life might prove to be short, he at last had some quiet. But then, he heard a continuous chugging and rattling. What was that? It was coming from outside, for sure. And then there was a shrill whistle, and Jay suddenly understood the source. It came from the railroad track about 8 kilometers away.

Normally Jay could not hear the train, not even its whistle, because of the distance and the countless obstructions of trees and houses between his apartment and the track. But tonight the temperature conditions were just right to bring him the sound the train sent somewhat upwards into the air. Normally that sound would just keep on going upward. However, when the upper air is warmer than the lower air, the path of the sound is bent over (refracted)by the transition from the cooler air to the higher warmer air and sent back toward the ground, bypassing all the obstacles along the ground. Jay was intercepting some of that bent-over sound.

Jay put his head back on his pillow. He had awakened with what sounded like a train bearing down on him. At least he could now go back to sleep with the almost comforting rattle of a distant train making its way through the night.